Intermittent inductive train control



Aug. 3 1926.

R. C. LEAKE INTERMITTENT INDUC'I'IVE TRAIN CONTROL Filed Sept. 27, 1924 2 Sheets-Sheet l Aug. 3 1926.

R. c. LEAKE INTERMITTENT mnuc'uvs TRAIN CONTROL.

2 Sheets-Sheet 2 Ifil'ed Sept. 27, 1924 Patented Aug. 3, 1926.

UNITED STATES Parser QFFICE.

RICHARD C. LEAKE, OF ROCHESTER, NEW YORK, ASSIGNOR T0 GENERAL RAILWAY SIGNAL COMPANY, "015 ROCHESTER, NEW YORK.

INTERMITTENT INDUGTIVE TRAIN CONTROL.

Application filed September 27, 1924. Serial No. 740,276.

This invention relates to automatic train control systems, and more particularly to influence communicating means of the intermittent inductive type.

Since it is believed that impulse transmitting means for train control systems should be effective at all speeds, in accordance with this invention it is'proposed touse magnetic induction or direct magnetic attraction, so as to assure operation at the lowest speeds. At high speeds, the track devlce and car-carried receiver of an intermittent system are in cooperative relation for a very short interval of time; and to assure reliable response of a movable armature in a system of such magnetic induction type, this invention further contemplates a construction of a receiver which is magnetized during the momentary passage over an active track device and utilizes such residual magnetism to shift a movable armature and also retain it in its shifted position.

A system' controlling the speed of the train is ordinarily of the cyclic type, requiring an initiating, operating or restricting impulse, and also a restoring, releasing or resetting impulse. For the restricting impulse, it is necessary to employ a track device which is sure to be always effective to produce the desired control; and according to this invention, apermanent magnet is used for this purpose. The releasing impulse, however, should be communicated only if all devices and circuits are functioning properly; and for this purpose an electro-magnet is employed.

Generally speaking, this invention contemplates a car-carried receiver having a magnetizable portion and a non biased movable armature, a permanent magnet adapted to magnetize the receiver and cause the armature to assume its operated or controlling position this permanent magnet being either always efiective or controllable, as desired, and an electro-magnet on the trackacting to magnetize the receiver with opposite magnetic polarity and causing the movable armature to be restored to its normal or noncontrolling position.

Other objects, advantages and characteristic features of the inventionin part will be apparent and in part pointed out hereinafter as the description progresses.

In the drawings, Figure 1 shows in a simment of the invention, and a car-carried receiver for cooperating with the track magnets, together with a simple form of speed control apparatus governed by this receiver; Fig. 2 shows in perspective the permanent track magnet and car receiver of Fig. l l in cooperative or superimposed relation;

F 1g. 3 shows a modified form of car receiver in superimposed relation to the permanent track magnet 'of'Fig. 1;

Fig. 4 shows a modified construction of the track magnets and their controlling circuits, a modified typeof receiver, and another form of speed control apparatus governed by the receiver and Fig. 5 shows in perspective the modified permanent track magnet and receiver of Fig. tin cooperative or superimposed relatlon.

Referring to Fig. 1, the track rails 1 are divided by insulating joints 2 into blocks in the usual way, one complete block I and the adjacent ends of two other blocks H and J being shown. Since the track magnets and control circuits for the several blocks are assumed to be the same, a description of the track equipment for the block I will suiiicefo-r all, corresponding elements in the other blocks being given like reference characters with distinctive exponents. 7

Using. the reference characters for the block I, each block is provided with the usual. normally closed track circuits, shown as comprising a track battery 3 and a D. C.

trackrelay 4-. A complete train controlsys tem embodying this invention may be installed with. orwithout the: usual trackway block signals; and semaphore signals Z are shownconventionally without attempting to illustrate their control circuits.

Associated with each block is a permanent track magnet Pfor transmitting operating orrestricting impulses to control train move ments in the corresponding block. The permanent magnet P for the block I is shown near the exit end of the next block H in the rear. Each of the permanent magnets P is of a general U-shape, made up of a plurality of bars of a cross section small enough to permit proper heat treatment, these bars being made of high grade. perpreferably kept as high as the clearances of the rolling stock, snow plows andthe like, will permit, in order to reduce the air gap between this magnet and its cooperating receiver. In the form of the invention shown in Figs. 1', 2 and 3, this permanent magnet P always provides an external magnetic fieldabove it throughwhich thecar receiver must pass. 7 V

Also associated with each block is a releasing or reset electro-magnet R, consisting ofa soft iron core of a general U-shape, solid or laminated as preferred, provided with enlarged pole pieces and a coil or winding 8, either on the legs, or on the back yoke as shown. This reset magnet R is disposed in the same relation to the track rails as the permanent magnet P, so as to have the same cooperative relation to the receiver on a passing car. In the embodiment of the invention shown in Fig. 1, therese't magnet R performs a dual function, so to speak, not only resetting to normal the speed control apparatus on the car after that apparatus has been in operation during the movement of the car through a block, but also cooperating with one of the permanentmagnets P to determine the transmission of an operating or restricting impulse. For this reason a reset magnet R is located a short distance ahead or in advance of each permanent magnet P with respect to the normal direction of traffic indicated by the arrow,

' so that trains will pass over thepermanent magnet first, this intervening distance being preferably as short as mechanical clearances and satisfactory operation will permit, ordinarily a few feet. On account ofits function and control, the reset magnet'R in Fig. 1, located near the exit end of'the block H a short distance in therear of. the insulated joints defining the exit end of the block, is conveniently considered as being associated with this block H, while the permanent'magnet P in the rear of this reset magnet R is conveniently considered as associated with the block I.

The winding 8 of each reset magnet is in a circuit including a suitable battery 10 and the front contact 9 of a line relay 6, so that this winding is energized if the next two blocks in advance of the corresponding block check relay 22.

are not occupied, the line relay 6 having an energizing circuit through the contact fingers and front contacts 5 and 7 of the track relays of these two blocks, as readily seen in the drawing. The reset magnet It, when'energized, provides an external magnetic field of opposite polarity to that of the permanent magnets P, as indicated in the drawing.

In Fig. 1 a locomotive or other vehicle has been represented diagrammatically by Supported a pair of wheels and axles 11. on this vehicle in any suitable manner, preferably from the body. or other spring supported member, is a receiver Ocdisposed so as to pass over the track magnets P and R and come intodirect superimposed relation thereto, as shown in Fig. 2. This receiver 0 comprises a magnetizable yoke or strap 12 of general U-shape,having its ends fastenedto soft ironpole pieces 13 and 14 The yokeor strap 12 is solid or laminated,as preferred, and is made of suitable magnetic material of a composition adapted to be readilymagnetized and yet retain residual magnetism to high degree.- In the air gap I or space between the pole pieces 13 and 14 is a movable polarized armature 15,- which is shown in a form similar to a shuttle type armature. This movablearmat-ure 15 is supported on an axis," preferably vertical,

through its center of mass on jewel or other anti-friction bearings; and this armature is polarized by a winding 16 energized from a car-carried battery 21, the energizing circuit for the winding 16 also'including a The armature 15 carries a suitable contact finger 18, adapted to engage an'insulated stationry contact, conventionally represented by the arrow 19, in one extreme position of said armature, stationlimits of motion of this armature. The armature 15 is not biased by a spring or otherwise, and is free to assume one or the other extreme position corresponding to the polarity of the residual magnetism in the yoke or strap 12.. 1 1

A modified type'of receiver Q, has been illustrated in Fig. 8, this receiver being shown in direct superimposed relation to a track magnet P. This. receiver Q, is similar in construction to'the receiver .0 described abovev in that it comprises a magnetizable yoke or strap 29 having two ends connected to soft iron pole pieces 30 and 31. The pole pieces in this type of receiver are bifurcated and provided with non-magnetic residual pins 38 as shown; and an armature, comprising the permanently magnetized pivotally supported bar 32, is mounted in the air gap between these pole pieces. The armature 32 carries a-suitable contact finger '84 adapted to engage an insulated station- 'ary stops 20 being used to define the extreme the arrow 35, in one extreme position of said armature. It is obvious that when this type of receiver is used, no armature energizing winding or check relay need be employed.

The receiver 0 may be used to control any suitable type of cyclic or speed control ap parat-us. In the simplified form of speec control apparatus shown in Fig. 1, a centritugal speed responsive device or centrifuge G is geared or otherwise suitably driven from an axle of the vehicle, this centrifuge being conventionally represented as of the well known fly ball type, which acts to draw a collar 2 1 downwardly against the opposition of a spring 25 as the speed of the vehicle increases. A speed arm 26 is pivotally supported near the centrifuge G and engages with the movable collar 24, so that this arm swings upward over'contact segments 27 and 28 as the speed of the vehicle increases. 7 v

The speed control apparatus includes some suitable form of air brake controlling mechanism, acting upon the usual air brake equipment to produce an automatic brake application. It is assumed that this brake applying mechanism will be controlled by an electro-pneumatic valve; and to indicate how the speed control apparatus of Fig. 1 acts to control the brakes, a conventional form of electro-pneumatic valve EPV has been shown with its control circuits.

Operation. Fig. J.Tlie parts of the car equipment are shown in Fig. 1 in the normal position, corresponding to clear traliic conditions, the running speed being assumed to be somethin more than the minimum speed (assumed to be about 15 miles per hour) and less than the maximum speed (assumed to be about 60 miles per hour). The electro-pneumatic valve EPV is energized by a circuit which may be traced as follows :Beginning at B, representing one terminal of a suitable source of car-carried electrical energy, contact finger 18, contact 19, wire 72, front contact 23 of check relay 22, wire 73, maximum speed contact segment 27 arm 26, wire 74;, valve EPV to C representing the other terminal of said source.

lVhile the train is traveling under a proceed or clear signal, with the parts of the car apparatus in the normal position shown in Fig. 1, a maximum normal running speed limit is enforced. If the train exceeds this speed limit, assumed to be about 69 miles per hour, the arm 26 is moved out of contact with the contact segment 27, thus deenergizing the valve EPV, and causing an automatic application of the brakes. l lhen the speed of the train has been reduced below this maximum speed limit, the valve EPV is again energized, and the engineer may release t-lie brakes and proceed, there being no penalty for exceeding the maximum speed limit.

The aolar'it ot the ma net P and the armai 1 Y e ture 15 is so selected that the flux from this permanent magnet passing through this 2131111 51110 tends to move the contact finger 18 against the contact 19. As the receiver O passes out of the magnetic field of the permanent magnet P, the residual magnetism in the strap or yoke 12 is free to act upon the armature 15, and this residual magnetism is or such polarity with respect to the polarity of the armature 15 as to cause 1 this armature to move the contact finger 18 away trom the contact 19, thereby opening the energizing circuit for the valve EPV.

Since this opening of the contacts 181'9 always happens at the track magnet P, irrespective of traffic conditions, it is preferred to make the valve EPV, or the brake applying mechanism controlled thereby, slow acting by some well known expedient, so that no actual application of the brakes occurs until after the lapse of a time following the opening of the contacts 1819, this time interval being suflicient to cover the time ordinarily taken by a train traveling from the track magnet P by the reset magnet B.

As the receiver 0 passes through the field or" the reset magnet'R, assumed to be energized, the flux from the magnet is collected by the soft iron pole pieces 13 and 1 1 and also passes through the armature 15 and the strap or yoke 12; but since the reset magnet R has a magnetic polarity opposite to the permanent magnet P, the flux through the yoke 12 is in the opposite direction, overcoming and neutralizing the residual magnetism placed in this yoke by the magnet P and leaving a residual magnetism of an opposite magnetic polarity. Vfhile the receiver 0 is passing through the field of the reset magnet R, the armature 15 tends to move ina direction to open the contacts 18-19, but atter the receiver leaves this magnetic field, the reversed residual magnetism in the yoke 12 acts upon the armature 15 to move it in a direction to close the contacts 18-49. It the winding 16 polarizing the armature 15 oi the receiver 0 should for any reason be wholly or partially de-energized, the check relay 22 in series with this winding opens its front contact 23 and de-energizes the valve EPV to apply the brakes.

The reset magnet lit at the entrance to. a caution or danger block is de-energized, as can be readily seen from the control circuits l l' 6'F" '1'-dl iocie me may in an Wien a train passes a caution or a stop signal, the receiver O passes through the magnetic field of the permanent magnet P only, with the slow action of the valve EPV or associated.

brake applying mechanism; and this brake application is maintained until the speed of the train has been reduced to a minimum speed, assumed to be about 15 miles per hour, whereupon the valve EPV is energized by a circuit through the low speed segment 28, arm 26, and wire 74, permitor strap tin the engineer to release the brakes and proceed at any speed less than this minimum speed. This minimum speed restriction persists until the train passes a clear signal, at

which the reset magnet R. is energized and acts to move the armature 15 in a direction to close the contacts 18 and 19 and maintain them closed. Y

zllodz'ficatz'on of Fig. 4.-Referring to Fig. l, which represents a modified construction of the type of train control system embodying the present invention, a section of trackway including one complete block L and the ends of two adjacent blocksK and M have been shown; and, using the reference charactersfor the block L, track batteries 86, track relays 3'7, and line relays 38 are provided, and operate in a manner identical with the corresponding trackway apparatus shown and described in connection with Figure 1. Associated with each block is a controllable permanent trackway' magnet PM for transmitting the operating or restricting impulses to control train movements in a corresponding block, this magnet PlVI for the block L being shown near the exit end of the next block'K in the rear. The controllable permanent magnet PM, which is shown in detail in Fig. 5, is ofigeneral U- shape and is made up of aplurality of bars of a high grade permanent magnet steel of a cross section small enough to permit proper heat treatment, these bars forming the yoke 43. The strap 4.3; is preferably providedwith soft iron pole pieces 4% and 45,

].&Vll1g soft iron leakage poles to and 47,

and twobuckingcoils 48. The controllable permanent magnet PMmay be disposed in diiierent ways'relative to the track rail-s,-but is preferably disposed in the same manneras the'permanent magnet P shown in Figure 1,

that is, crosswise of and between the track rails, with the pole pieces tl and l5 extending pwardly as far as the clearance of the rolling stock will permit. The bucking coils l-S are. energized by a circuit including the battery and the contact finger 79 of the line relay 38, the energization of these coils being arranged to produce a flux which will directly oppose and so neutralize the flux produced by the permanently magnetized yoke 43. The leakage poles i6 and i? partially shunt the yoke 43,

thus preventing the de-magnetization of this contacts 81 and 82 of the trackrelay's of these blocks as readily seen in the drawings. A releasing or reset electro-magnet R,

identical with the reset'magnet described in connection with F1g'ure 1, 1S associatedwith each block and is 'disposedin the same relation to the track rails as thecontrollable magnet PM so as to have the same cooper ative relation to the receiver on a passing car or vehicle. in the embodiment shown in Figure 4, the reset magnet It acts to reset the car-carried speed control apparatus only,

and hence is located a short distance in the rear of the insulating joints at the exit end of the block with respect to the normal direction of traliic, this intervening distance being preferably relatively short, ordinarily a few feet, and less than a car in length. As in the embodiment shown in Figure 1,

the reset magnet R is conveniently considered as being associated with the block K,

while the controllable permanent magnet PM is considered as being associated with the block L. In the embodiment shown in Figure 3, the reset magnet R and the controllable permanent magnet PM operate independently; and for this reason the controllable permanent magnet PM, associated with the block L, may be located at any point in this block or in the rear'of this block, providing that the distance between the permanent magnet PM and the exit end of the block L is long enough to provide safe braking distance for the'trainsr f the magnet PM is located in theblock L, the energizing circuit for the bucking coils 48 of this magnet are controlled by a contact of the track relay 37 so that a train entering thisblock under clear traffic conditions will not be restricted by its own presence in the block, as wouldbe the case if the bucking coils were energized from the line relay 38.

The winding 40 of the reset magnet R associated with a given block is energized through a circuit including the battery 42 and the contact finger a1 and front contact of the track relay 37 of the next block in advance so that this winding is energized if the said advance block is not occupied.

As indicated in the drawings, the reset magnet B when energized, provides an external magnetic-field of a polarity opposite to that of the controllable permanent magnet PM.

In Figure 4, a locomotive or other vehicle has been represented diagrammatically by a pair of wheels and axles 48. Supported on this vehicle in any suitable manner, preferably from the body or other spring supported member, is a receiver OD, disposed to pass over the trackway magnets PM and R in direct superimposed relation thereto, as shown in Figure 5. This receiver OD is somewhat similar to the receiver 0 shown in Figure 1, comprising a magnetizable yoke or strap 49 of general U-shape, having soft iron pole pieces 50 and 51. The yoke or strap 49 is made of the same material as the strap 12 of the receiver 0, being solid or' position of this armature, stationary stops 54 being used to define the extreme limits of motion of the armature.

The receiver OD may be used to control any suitable type of train control apparatus, and for the purpose of illustration, has been shown as controlling apparatus of the well known cam and governor permissive speed type. As this type of brake control apparatus is now well known in the art of train control, it will be described in a brief manner only. A" centrifugal speed responsive device or centrifuge F is geared or otherwise suitably driven from the wheels of the vehicle and operates to rock a speed lever 58 clockwise as the speed increases. The

free end of the lever58 is pivotally connected.

to'the lower end of a floating lever 60'; and the other end of thefioating lever 60 carries 1 a roller bearing against a permissive speed cam 61. This cam 61 is arranged to be driven in acordance with the; progress of the vehicle by a distance shaft ,62, a mutilated gear 63, and a shaft Get-which is operatively connected to an axle of the vehicle. The shaft 64: carries a worm 65 whichis normally held out of engagement with the mutilated gear 63 by the cam starter magnet CS; and upon the de-energization of this' magnet, the worm 65 and gear 63 are caused to engage by the sprlng 66. The distance shaft 60 is returned to its normal position upon" the disengagement of the worm 65" from the mutilated gear 63 by means of a spring 67. It is obvious that the movement of any intermediate point of the floating lever 60 is dependent upon a fun'ctiono f the vehicle speed and its distance of travel from the point at which the cam starter magnet CS was de-energized. A pivotally mounted contact operating sector 68 is connected to gers 71 which are normallybiaseol to their open position. a It is evident that, as the vehicle speed increases, the lower end of the floating lever 60 is moved to the left, turn ing'the contact operating sector 68 in a clockwise direction, until a point is reached, depending on the position of the cam 61, where'the contact fingers 71 are opened. An electrdpne'umatic valve EPV is provided; and, as in the case of the valve EPV described in connection with Fig. 1, it is as sumed that this valve acts" to initiate some suitablebrake applying apparatus upon the de-energization of a circuit through its windings, this circuit being closed through the contact fingers? 1 as clearly shown in the drawings.

Operation. Figure 4.The parts of the car equipment are shownin Figure 4 in the normal'position, corresponding toclear traffic conditions, the running speed being assumed to be something more than the minimum speed (assumed to be about 15 miles per hour) and less than the maximumspeed (assumedto be about 60 miles per hour); The valve EPV is energized by a circuit which'includesthe contact fingers 71 of the contact operating sector" 68, which" circuit may be readily'traced.

While the train is traveling under a pro-- ceed or clear signahwith the car equipment in the normal position as shown in Figure t,a maximum normal running'speed limit isimposed. As the'trainspeed increases,

the sp'eedlever '58 moves the lower end of the floatinglever 60 to the left, and rotates thecontact sector 68' in a clockwise direcmum no'rinal runninglimit,"assumed to be 60'miles per hour, the sector68 will be lot turnedto a positio'nsu'chthatits associated contact lingers 71 will be opened de-ener j giz'n'ig the valve EPV, and thus causlngan automatic brake application which will er sist untilithe' train speedjhas been reduced to a value belowthe maximum limit, whereupon the valve EPV will be re-ener'gizedf and the train may proceed without penalty; 1

As the train passes aclear or proceed signal 1n enterlnga clear bloclgthe receiver OD first passes over the energized reset electramagna'n and their over the controllable permanentmagnets PM,the bucking coils 48 of which are energized so that the 'permanent magnetism of this magnet PM is bucked back or neutralized. As the receiver OD passes through the external magnetic field of the reset magnet It, the flux collectedby the pole pieces 50 and 51 passes through the strap 49 and the armature 52.

The polarity of the magnet R and the armature 52 is so selected that the flux from this reset magnet passing through this armature tends to move the contact fingerv 55 against its associated stationary contact '56; but, since under the normal COIldlllQll of car apparatus assumed the armature 52 1s already in this position, there is nornovement. As

the receiver OD passes "out of the magnetic field of thereset electro-magnet, R, the

residual magnetism left in the strap 49 by this field acts upon the armature 52 tohold this armature in this same position, keeping its contacts 55 and 56 closed. The receiver OD next passes the controllable permanent magnet PM; but as the bucking coils 48 of this permanent magnet PM- are energized under the clear condition assumed, no flux passes through the strap 49 of the receiver and the armature 52 remains in a position to close itscco'ntacts 55and 56. v With the contacts 55 and 56 closed, the

cam starter magnet OS is. maintained energized through a circuit which may be traced as follows :Beginning at the battery ter-- minal B, through the contact finger 55 and stationary contact 56 of the armature 52,

wire 78, contact finger 7 6 and front contact of check relay 77, Wire 7 5 and the winding of the cam starter magnet OS to thebattery terminal O. 'VVith the cam starter magnet OS energized, the train may proceed in the clear block without restriction other than the maximum speed limit restriction explained above. I s 7 As a train equipped with the apparatus of 4 approaches a caution signal at the entrance to a. block which is not occupied but which is followed by an occupiedblock,

of a polarity opposite to that produced by.

the reset magnet R is set up by'the permanently magnetized strap 43 of the magnet PM; and this field causes a reversal of the residual magnetism in the yoke 49 ofthe receiver OD. The residual magnetism of reversed polarity in the yoke 49 swings the armature, 52 to a position to open its contacts. v;

55 andr56 and to maintain the armature in such position until an energized reset magnet is encountered. I ,L

i The opening of the contacts 55 and 56 deenergizes the cam starter magnet CS whichv causes theworm 65 to engage the mutilated gear 63, thereby causing the distance shaft 62 to rotate and set up more andmore restrictive speed limits by means of the permissive speed cam 61 which engages the I floating lever 60 as-described above. Ifthe trainspeed at any point exceeds the permissive speed imposed by the permissive speed cam 61 and its associatedmechanism, the

contact fingers 71 open and the valve EPV- is de-energized, causing an automatic brake application, which is maintained until the train speed is brought below the existing permissive speed limit. After the mutilated gear 63 has been rotated through approximately 180 degrees, the worm 65 will engage the mutilated portion of the mutilated gear, and its rotation will be stopped at this point. With the distance shaft 62 in this extreme rundown position, the permissive speed cam 61 will maintain the floating lever 60 in a position to impose a minimum speed restriction, assumed to be 15 miles per hour, at wlnchspeed thetrain may proceed to the end of the caution block, and also on into a dangeroroccupied block.

If caution traific conditions exist in the next block encountered, the magnetic field set up by the next reset electro-magnet R passes through the strap 49 of the receiver inc OD, with the result that the contacts55 and 56 of this receiver are again closed and the cam starter magnet OS energized, disengaging the'worm 65 and the mutilated gear 63 and thus allowing the distanceshaft 62 to be reset to its initial position by the spring 67. Assuming a caution block, the controllable permanent magnet PM is in its active condition, and thecontacts 55- and 56 of the,

receiver OD will be immediately re -opened,

the cam starter magnet OS de-energized, and the progress of the tram 1n this caution block will be restricted as described above.

At a danger signal, that is, signal at the entrance to an occupied block, the reset magnet R is de-energized by the retraction of the contact finger-41 of the track relay of such danger block; and the controllablepermanent magnet PM is in its active condition by reason of the de-energization of the line relay 38, assuming this magnet PMis located and controlled as shown. As the train approaches the danger signal, the receiver'OD first passes the de-energized reset magnet R with the result'that the residual magnetismin the strap 49 of thereceiver remains unchanged and the cam startermagnet OS remains de-energlzed, maintaining the minimum speed limit. As the receiver OD passes through the field of the controllable permanent magnet PM, the residual magnetism in the strap 49, acting to hold the armature 52 of this receiver in position to open its contacts, is not reversed, being increased if anything, and these contacts remain open, maintaining the cam starter magnet de-energized and so permitting the train to proceed in the danger block at the minimum speed only. This minimum speed limit is maintained until the receiver 0]) passes an energized reset electro-magnet B at the entrance to a caution or a clear block.

As in the case of the receiver 0 described in connection with. Fig. 1, if the winding 53 polarizing the armature 52 for any reason becomes wholly or partially de energized, the check relay 77 in series with this Winding opens the front contact 76, so de-energizing the cam starter magnet CS and initiating a restrictive brake control.

A receiver having a permanently magnetized armature may be used with either of the systems illustrated in Figs. 1 and l, a receiver of this type, adapted for use with the system of 1, being shown in Fig. It is obvious that with a permanently magnetized armature, no polarizing winding is needed and hence the check relay and its associated contacts are omitted from the system when this type of arn'iature is used. It is preferable to provide residual pins, as the pins 33 in Fig. 3, and to prevent the demagnetization of the permanently mag netized armature by means of the fiux impressed on the magnetic circuit of the re ceiver by the trackway magnets.

It should be noted that when an operating receiver of the type shown in Figs. 2 andB passes over a trackway magnet, the magnetic flux of said magnet passes through two iarallel paths, one path being through the strap or yoke 01 the receiver and the other being through the soft iron pole pieces and the armature. For this reason the armature will be momentarily swung in a direction opposite to that caused by the residual magnetism remaining in the strap or yoke after the receiver leaves the field of the trackway magnet. In order to prevent the armature from effectively shunting the strap or yoke and so preventing its proper magnetization, this armature in the type shown in Fig. 2, may be partially or wholly constructed of non-magnetic material in order to increase the reluctance through this path and thereby causing a large portion of the fin from the trackway magnet to pass through the strap or yoke of the receiver. In the type of operating receiver shown in Fig. 3, the air gap may be lengthened and the residual pins 33 may be enlarged to accomplish; this result. It should be noted that this increase in the reluctance in the magnetiepath through the armature will. re

duce the flux due to the residual magnetism I in the strap or yoke of the receiver, and for this reason the reluctance of this path can. only be increased to an extent consistent with. the proper operation of the armature by means of this residual magnetism. In the type of operatin receiver shown in Figure 5, the flux caused by the trackway magnet passes through one path only, that is, through the armature and strap in series; and the residual magnetism maintained in the strap or yoke 49 is in. the same direction as the flux setting up this residual magnetism. For this reason the armature 52- used in the operating receiver shown in Fig. 5 is preferably made of a magnetic material, such as soft iron.

If a receiver of the type shown in Figs. 2 and 3 is used in connection with the type of train control system shown in Fig. 4, the

momentary swinging of the armature in a direction to close its contacts, as the receiver passes over an active controllable permanent magnet PM associated with a danger block, may cause an energization of the cam starter magnet and a consequent return of the distance shaft 62 to its initial position as the train enters or passes through such danger block, thus allowing the train to proceed at a speed in excess of the minimum limit which should be in effect in danger territory. For" this reason it is thought preferable to employ the type of operating receiver shown in Fig. 5 in connection with the cainand governor type of speed control system; or

to provide some suitable means not shown) for preventing the resetting of the distance shaft by a momentary energization of the cam starter magnet when the type of receiver shown in Figs. 2 or 3 is used.

In the types of operating receivers shown in Figs. 2 and 5, a magnetic field is ,pro duced by the armature polarizing windings 16 and 53. In order that these magnetic fields may not oppose and so weaken the residual fields in the straps or yo'kes l2 and 49, the armature is arranged in a. position such that its magnetic" field is substantially at right angles to the residual field, and its motion is limited to a very small angle of rotation by means of suitable stops, so that the field caused by the armature windings will be a cross magnetizing field rather than a de-magnetizing field.

As the influence transmitting means embod'ying the present invention has been de scribed in connection with two rather specific types of automatic train control. systems and as rather specific forms of transmitting means have been shown and described, it should be clearly understood that the invention is not limited in its scope to the specific forms oftransmitting means or train control system's shown. The novel influence transmitting means may be, advantageously used with any type of intermittent inductive train control systems, and many changes, modifications and combinations may be in cluded in such systems without departing from the spirit of the presentinvention.

lVha-t it is desired to secure by Letters Patent is 1. In an automatic train control system, means for transmitting control influences corresponding to traiiic conditions from the trackway to a vehicle comprising trackway magnets, magnetized in accordance with traiiic conditions ahead, and a car carried receiving device having a magnetic circuit capable of retaining a residualmagnetism of a polarity corresponding to the, magnetism of said trackway magnets.

2. In an automatic train control system, in combination with car-carried apparatus for controlling the brakes of a vehicle, means for transmitting control influences from the trackway to a vehicle comprising, magnets at spaced points along the traclzway, magnetized in response to traffic concitions ahead, a car-carried magnetic receiving de-,

vice having a magnetic circuit capable of retaining aresidual magnetism of a polarity corresponding to the magnetization off said trackway magnets, and means in said magnetic circuit responsive to the polarity of said circuit and oaerating to control said brake control apparatus.

3. In an automatic train control system, in. combination with car-carried apparatus for controlling the brakes of a vehicle, means for transmitting control influences from the trackway to a vehicle comprising pairs of magnets located at spaced points along the trackway, circuits for controlling the energization of at least one of said magnets in accordance with traiiic conditions ahead, a car-carried receiving device'havmg amagnetic circuit with an armature therein, said magnetic circuit being selectively magnetizable with a polarity corresponding to the relative energization of said series of tracln way magnets, and said brake control apparatus being actuated by a circuit controlled by said armature. I

' l. In an automatic traincontrol system in combination with car-carried brake control apparatus, means for controlling said brake control apparatus comprising a trackway electro-magnet and a trackway permanent magnet, said traclrway electro-magnet being energized and said t-rackway permanent magnet being rendered inactive under clear traffic conditions ahead, and a car-carried receiving device having an element which is responsive to the magnetization of said trackway magnets, said element acting to control said brake control apparatus.

5. In an automatic train control system in combination with car-carried brake control magnet havi coils for apparatus, traclrway magnetic means whose magnetism is controlled in accordance with trafiic' conditions ahead, a car-carried magnet-i0 receiver having a member which is magnetizablein accordance with the magnetism of said trackway magnetic means, an armature in the magnetic path of said magnetizable member and a normally energized winding on said armature, means for controlling said brake control apparatus in accordance with the movement of said armature, and means whereby the cle-energization or" said armature winding will cause a brake application.

(5. In an automatic train comirolisystem, in combination with car-carried apparatus for controlling the brakes of a vehicle, means for transmitting control influences from the trackway to a vehicle comprising a trackway electro-magnet and a trackway permanent nuwnehsaid traclrway electro-magnet being energized in response to clear trafiic conditions ahead and said trackway permanent -i opposing its normal flux, said coils being energized under clear trailic conditions ahead, and a car-carried receiving device having a member which is magnetizable in accordance with the energization of said .trackway magnets, and means i'cr actuating said brakecontrol magnets in accordance with the energization of said car-carried magnetic member.

7. In an automatic train control system, in combination with car-carried brake control apparatus, means for transmitting control iniuences from the tracliway to a vehicle comprising a trackway permanent magnet and a trackway electro-magnet, said trackway elect-ro-magnet being energized in response to clear traflic conditions ahead, and a car-carriedcreceiving device having a magnetic circuit, said magnetic circuit retaining a residual magnetism of a polarity corresponding to the magnetism of said trackway electro-magnet under clear traffic conditions ahead, and means for actuating said car-carried brake control apparatus in accordance with the polarity of the residual magnetism of said car-carried receiving device. I

8. In an automatic train control system,-

in combination with car-carried brake control apparatu initiated in response to the cle-energization of an electrical control device, means for transmitting control iniluences corresponding to trafiic conditions from the trackway to a vehiclecomprising trackway magnets magnetized in-accordance with traffic conditions ahead, and a car-carried receiving device having a magnetic circuit magnetized in accordance with the magnetism of said trackway magnets, an armature in series with said magnetic circuit, said armature operating 'a contact for controlling the energization of said electrical control device, whereby said brake control apparatus is initiated in accordance with traffic conditions ahead.

9. In an automatic train control system, car-carried b 'ake control apparatus initiated in response to the de-energization of an electrical control device, means for controlling the energization of said electrical control device, comprising a trackway electro-magnet energized in response to clear traflic con ditions ahead, a trackway permanent magnet having bucking coils for opposing the normal flux of said permanent magnet, said bucking coils being energized in response to clear traflic conditions ahead, and a car-carried receiving device comprising an element composed of magnetizable material containing an electrically energized armature, said element being arranged to retain a residual magnetism of a polarity corresponding to the magnetism of said trackway magnets, and an energizing circuit for said electrical control device containing contacts controlled by the movement of said armature, and by the cnergization of said armature.

10. In an automatic train control system, in combination with vehicle carried apparatus acting when init-iatedto cause an auto matic brake application at increasingly restrictive speed limits as the vehicle travels from the point at which said apparatus is initiated, means for initiating said apparatus under unfavorable traflic conditions ahead comprising, magnets at spaced points cuit capable of retaining a residual magnetism oi? a polarity corresponding to the magnetization of said trackway magnets, and means in said magnetic circuit responsive to the polarity of said circuit and operating to control said apparatus.

11. In an automatic train control system, in combination with car carried permissive speed apparatus acting when initiated to cause a brake application at an increasingly restrictive speed limits as the vehicle proceeds from the point at Which said apparatus is initiated, means for controlling the initiation of said apparatus from the trackway in accordance with the traflic conditions ahead comprising pairs of magnets located at spaced points along the trackway, circuits for controlling the energization of at least one of said magnets in accordance With traflic conditions ahead, a car carried receiving device having a'magnetic circuit with an armature therein, said magnetic circuit being selectively magnetizable with a polarity corresponding'to the relative energization of said series of trackway magnets, the initiation of said permissive speed apparatus being controlled by said armature.

In testimony whereofl my signature.

RICHARD C. LEAKE. 

